Global Honeybee Colony Trend is Positively Related to Crop Yields of Medium Pollination Dependence

Abstract

Recent declination of pollinators especially honeybee population in different geographical locations could threaten agricultural productivity leading to food insecurity. In order to examine the impact of the ‘pollinator crisis’, we hypothesized that the level of pollinator-dependence among the crops would be a significant factor to influence the crop yield. We examined the relationship between honeybee (Apis mellifera) population as a major insect pollinator and crop yields with varying pollinator dependence in two different geographical scales, the continental scale and the country. Yield data of 60 crop systems with varying pollinator dependencies and the colony size of honey bee (i.e., the number of bee hives) in 5 continents (Asia, Europe, Africa, Australia and Americas) over the period of 1983-2013 were obtained from FAO database. We emphasised two Asian countries, for instance, Republic of Korea and India, considering socioeconomic development status to examine more closely the pattern in a finer scale. The temporal pattern of honeybee colony was categorized into three levels, increasing, decreasing and stable. Regression analysis showed that honeybee colony pattern was positively correlated with little, modest and great pollinator dependent crops but negatively correlated with essential pollinator dependent crops. In two Asian countries analyzed for this study, Republic of Korea and India showed the same pattern of honeybee colony increase but with different rates and densities. Increased yields observed in crops with medium pollination dependence could have resulted from the increase of honeybee hive numbers, but the yield change of essential pollination dependent crop seemed more related to the socioeconomic condition.